Derivative Financial Instruments (Schedule of Interest Rate Swap Activity Recorded in the Consolidated Financial Statements) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	$ (221)	$ (204)	$ (207)
Other income (expense), net	14	7	4
Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense	(59)	(68)	(63)
Other income (expense), net	$ 0	$ 0	$ 0